ISBN 9783843918701

978-3-8439-1870-1, Reihe Thermodynamik

Alexander Nann
Thermodynamics for the Extraction of Biobutanol Using Ionic Liquids (Band 13)

195 Seiten, Dissertation Technische Universität Dortmund (2014), Softcover, A5

Zusammenfassung / Abstract

The development of an efficient extraction process for biobutanol production using ionic liquids (ILs) requires knowledge of the thermodynamic behavior of IL systems. These data are accessible by measuring and modeling thermodynamic properties.

In this work, binary 1-butanol/IL solutions were experimentally investigated: the ILs studied were [Im10.1]+[tcb]-, [Mo10.1]+[tcb]-, [Im10.1]+[ntf2]-, and [Mo10.1]+[ntf2]-. Activity- coefficient data over the entire concentration range were obtained by combining the experimental data of the methods: vapor-pressure osmometry (VPO), headspace-gas chromatography (HS-GC), and gas-liquid chromatography (GLC). Ion-specific association and molecular-interaction behavior for the investigated ILs were identified as a function of the composition and the type of anion-cation combination. It was found that the ILs in 1-butanol tend to form ion associates even at low IL concentrations and the specific (1- butanol)-IL interactions of the ILs increase in the order: [Mo10.1]+[ntf2]- < [Im10.1]+[ntf2]- < [Mo10.1]+[tcb]- < [Im10.1]+[tcb]-; the IL [Im10.1]+[tcb]- exhibits the strongest (1-butanol)-IL interactions of the considered ILs and shows the highest affinity towards 1-butanol. The experimental data were modeled with the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) using a molecule-based approach for ILs. The PC-SAFT parameters for ILs were determined by fitting to pure-IL densities, VPO data and 1-butanol activity coefficients at infinite dilution. Without introducing any binary interaction parameter for 1-butanol/IL systems, PC-SAFT was able to accurately describe the experimental data.

Furthermore, the liquid-liquid equilibria (LLE) of ternary 1-butanol/water/IL mixtures were measured at temperatures of 308.15 and 323.15 K. The already determined PC-SAFT model parameters for ILs were used to predict the LLE behavior. Binary interaction parameters for 1-butanol/water and water/IL pairs were determined by fitting to the respective binary LLE data. The LLE predictions of the ternary systems were evaluated with experimentally determined LLE data and with 1-butanol distribution coefficients and selectivities of 1-butanol over water. Without introducing any additional parameters or refitting existing PC-SAFT parameters, the ternary LLEs of 1-butanol, water and an IL, the very sensitive properties 1-butanol distribution coefficient and the selectivity of 1-butanol over water were predicted with high accuracy.